CPC Plant Profile: Eastern Prairie White-fringed Orchid
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Plant Profile

Eastern Prairie White-fringed Orchid (Platanthera leucophaea)

This shot is a closeup of the eastern prairie fringed orchid. Photo Credit: Pati Vitt
Description
  • Global Rank: G2 - Imperiled
  • Legal Status: Federally Threatened
  • Family: Orchidaceae
  • State: IA, IL, IN, ME, MI, MO, NY, OH, OK, ON, PA, VA, WI
  • Nature Serve ID: 134537
  • Date Inducted in National Collection:

P. leucophaea is one of the largest and showiest of the native North American orchids. It is one of at least 200 North American orchid species, and is currently listed as Federally Threatened. This species has declined in the United States by more than 70 percent from original county records. This decline is due mainly to habitat loss for cropland and pasture. The 30 percent of original populations that remain are threatened by non-native species, illegal collection, and continued habitat loss. Most remaining populations are small (fewer than 50 plants), and only about 20 percent of these have adequate protection and management. The species is also found in Canada, but is now known from only 12 populations. (USFWS 1999, Brownell 1984) Eastern prairie fringed orchid is a perennial orchid, with an upright leafy stem extending up to 40 inches high from an underground tuber. Its leaves sheath the stem, and are 2-8 inches long, elliptical to lance-shaped, and progressively larger toward the stem base. The inflorescence extends above the leaves, with 5-40 creamy white flowers subtended by lance-shaped bracts. The flowers are distinguished by a 3-parted fringed lip 1.5-3 cm long and a nectar spur 1-2 inches long. This species has a close relative, Platanthera praeclara, which occurs to the west of the Mississippi River. This species is aptly named the Western prairie fringed orchid, and each have somewhat different flower morphologies, likely because they evolved in the presence of different pollinator species. (Sheviak and Bowles 1986)

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Updates
Center for Plant Conservation
  • 11/25/2021
  • Reintroduction

In 1994, The Nature Conservancy initiated an 80 acre wetland restoration within previously cultivated lands at their Nachusa Grasslands Preserve in north central Illinois by removing and dismantling over 3 miles of field tile systems. Based in part on prior successes of introductions of Platanera leucophaes in the Chicago Region, efforts to pollinate and collect seeds from a Lake County, IL population and introduce them to the TNC preserve were approved.

In October, 1995, an unknown number of seeds from five flowers were mixed with a fair amount of sand, and hand-spread across a five acre portion of the recently restored wetland on predominantly bare, silt-loam and muck soils. No additional site preparation or seeding efforts were made.

Annual surveys for plants were made in July of each following year, beginning in 1996. No plants were observed until 2002, when seven flowering individuals were observed. Those plants were subsequently caged to protect them from deer browse, and have persisted through 2007, the last date a census was conducted.

  • 09/23/2020
  • Reintroduction

Reintroduction using dispersal of seeds from hand pollinated plants has shown that flowering plants may appear in as few as three years. (

  • 09/23/2020
  • Reproductive Research

Research on reproductive biology is examining how different levels of outcrossing affect seed production and seed viability, and how seed production (when enhanced by hand pollination) may affect the longevity of individual plants. (Vitt 2000)

  • 09/23/2020
  • Demographic Research

Demographic monitoring has shown that most plants have a short life-span, often flowering only once. As a result, seed production appears to be an important life history stage and demographic process in population maintenance.

  • 09/23/2020
  • Genetic Research

Genetic surveys using allozyme and RAPDs techniques have found that populations may have relatively high levels of genetic diversity, and that genetic differentiation may occur among populations

Nature Serve Biotics
  • 05/02/2017

Relatively wide ranging species but many sites are extirpated (some estimates as high as 70% reduction across range). Most of this species' wet prairie habitat has been destroyed due to drainage and conversion to agriculture, fire suppression, and intensive mowing. Because of the destruction of most of the natural grasslands east of the Mississippi River, large populations no longer occur anywhere in the United States. The mostly small, isolated populations that remain are not representative of populations supported by the once-vast prairie habitat. Because of fire suppression and changes in hydrology remaining sites require active management. As of 2010 with active management, 78% of populations are stable or increasing. However, 83% have severe to moderate management needs.

Marlin L. Bowles
  • 01/01/2010

Threats include (USFWS 1999): Most Platanthera leucophaea populations have been lost through destruction and modification of habitat - primarily conversion of habitat to cropland and pasture. Alteration of hydrology, fire protection, and development

Marlin L. Bowles
  • 01/01/2010

As stated in the U.S. Fish and Wildlife Service's Recovery Plan: The eastern prairie fringed orchid has declined more than 70% from original county records in the United States. Most remaining habitats are small, with fewer than 50 plants, and are not representative of the once vast prairie populations of this orchid. A few populations, primarily in successional vegetation, number in the hundreds or thousands. About 60 populations are extant in Iowa, Wisconsin, Illinois, Michigan, Ohio, Indiana, and Maine. Plants have not been relocated in New York, Pennsylvania, New Jersey, or Oklahoma.

Marlin L. Bowles
  • 01/01/2010

Research is focusing on genetic analysis, demographic monitoring, reproductive biology, and propagation and introduction techniques. Genetic surveys using allozyme and RAPDs techniques have found that populations may have relatively high levels of genetic diversity, and that genetic differentiation may occur among populations. Demographic monitoring has shown that most plants have a short life-span, often flowering only once. As a result, seed production appears to be an important life history stage and demographic process in population maintenance. Research on reproductive biology is examining how different levels of outcrossing affect seed production and seed viability, and how seed production (when enhanced by hand pollination) may affect the longevity of individual plants. (Vitt 2000) Reintroduction using dispersal of seeds from hand pollinated plants has shown that flowering plants may appear in as few as three years. (Packard 1991; Keibler 1994, 1995, 1998, 2000) Laboratory work has identified mycorrhizal fungi species associated with plants, and has developed techniques for propagating seedlings in association with these soil fungi. (Zettler et a. 2001)

Marlin L. Bowles
  • 01/01/2010

Management of tallgrass prairie populations has focused on using prescribed burning to maintain vegetation composition and structure, and to promote flowering of orchids. Management to reduce invasion by alien species, primarily smooth buckthorn, has used cutting and application of herbicides. Some hydrology management has focused on removal of drain tiles to restore original drainage.

Marlin L. Bowles
  • 01/01/2010

Continued demographic monitoring is needed to provide a better understanding of the viability of orchid populations. Important questions are whether small populations are viable, and whether large population that occur on successional habitats can be maintained. More research is needed to understand the relationship between mycorrhizal fungi and the longevity of orchids.

Marlin L. Bowles
  • 01/01/2010

Work is needed to determine whether ex-situ populations can be maintained, and whether propagation techniques can be developed to produce propagules that can be used for restoration.

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Nomenclature
Taxon Platanthera leucophaea
Authority (Nutt.) Lindl.
Family Orchidaceae
CPC Number 3520
ITIS 43431
USDA PLLE2
Common Names Eastern prairie fringed orchid | prairie fringed orchid | prairie orchis | prairie white-fringed orchid | white-fringed orchid | prairie white fringed orchid
Associated Scientific Names Platanthera leucophaea | Blephariglotis leucophaea | Habenaria leucophaea | Blephariglottis leucophaea | Fimbriella leucophaea | Orchis leucophaea
Distribution The eastern prairie fringed orchid formerly ranged westward into eastern Iowa and Missouri, with a disjunct type locality in southeastern Oklahoma. It occurred eastward in a narrowing peninsula acros
State Rank
State State Rank
Iowa S1
Illinois S1
Indiana S1
Maine S1
Michigan S1
Missouri S1
New York SH
Ohio S2
Oklahoma SH
Ontario S2
Pennsylvania SX
Virginia S1
Wisconsin S2
Habitat

The eastern prairie fringed orchid requires full sun for optimum growth and reproduction. It occupies tallgrass silt-loam or sand prairies, sedge meadows, fens, lakeshore grasslands, and occasionally sphagnum bogs in the eastern part of its range. (USFWS 1999)These habitats occur across six physiographic regions. The unglaciated Ozark region supports sedge meadow habitat, from which Platanthera leucophaea is apparently extirpated. Kansan glacial soils support prairie habitat, primarily west of the Mississippi River. East of the Mississippi River, Wisconsinan glacial soils support prairie, sedge meadow, and peatland habitat. The lake plains of the Lake Michigan, Lake Huron, and Lake Erie basins support prairie habitat. Disjunct eastern populations also occur in unglaciated sedge meadow, and formerly occurred in unglaciated prairie in Oklahoma.

Ecological Relationships

Platanthera leucophaea occupies a wide range of soil pH conditions. Tallgrass silt loam and sand prairie soils are usually calcareous, with pH levels of 6-7.5. Soils tend to be more acid in lake borders, fens, sedge meadows, and marshes in the eastern parts of its range, with pH levels ranging from 5.3-6.5. In graminoid fens, this orchid appears to avoid highly calcareous conditions, occupying substrates that have poor to intermediate nutrient levels. Plants found in sphagnum tamarack bogs may root below the sphagnum layer in a more calcareous substrate, or may occur in younger advancing sedge mats. Both high precipitation levels and fire have been suggested to promote flowering of Platanthera leucophaea in tallgrass prairie habitat, but moisture levels appear to be an overriding factor. Over a twelve-year period in Illinois, percent flowering in P. leucophaea populations was higher in wetland habitat and was positively correlated with growing season rainfall. Over time, flowering plants also appeared more quickly in wetland habitat after a severe 1988 drought. Thus, burning would most likely promote flowering in tallgrass prairie wetlands or during years of high growing season rainfall. White fringed orchids require hawkmoth (SPHINGIDAE) pollination for sexual reproduction. The flowers are nocturnally fragrant and place pollinia on the proboscises of hawkmoths as they ingest a high-volume nectar resource from long nectar spurs. As in most orchids, the flowers are morphologically adapted to outcrossing, but plants appear to be self-compatible and probably receive high levels of self-pollination in small populations when pollinators revisit inflorescences. (Bowles 1983, 1985)Specific requirements for Platanthera leucophaea seedling establishment are not well known. Seed germination may be light-inhibited, with dormancy broken by darkness and moist stratification; but successful seedling establishment requires mycorrhizal development with a favorable soil-inhabiting fungus. Seedlings may persist for several years as subterranean protocormbs, receiving nutrients from the fungus. This relationship becomes symbiotic once the plants can produce leaves, and it is likely not species-specific for orchids or fungi.Disturbance may be important in Platanthera leucophaea seedling establishment. Patch disturbance regimes or early-successional vegetation stages are critical for seedling establishment of disturbance-adapted plants, and terrestrial orchids are well known for colonization following disturbance. Platanthera leucophaea populations reach highest densities in disturbed habitats or early- to mid-successional plant communities. Soil fungi responsible for orchid seedling establishment might also respond to similar disturbance or successional patterns. Under apparently favorable conditions or in successional habitats, flowering P. leucophaea have appeared as soon as 5 years after seed dispersal. The root systems of terrestrial orchids are reduced, and evidently require mycorrhizae for proper water uptake and nutrition especially under stress. (Annual tuber regeneration in orchids may also require reinfection by mycorrhizae. Thus the stability of orchid populations is closely related to the ecological conditions of their mycorrhizae, which may be in part regulated by the increased mycorrhizal productivity that occurs after spring burning of prairie. This relationship is dynamic; orchids occasionally enter dormancy (possibly with mycorrhizal nutrition), or decline as mycorrhizae become reduced. Although Platanthera leucophaea is pre-adapted to dormant season disturbances such as prairie fires, growing season damage to vegetative material may weaken plants by limiting food storage.

Pollinators
Common Name Name in Text Association Type Source InteractionID
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting
The Nature Conservancy Illinois Reintroduction 1996

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